Red-shifted substrates for FAST fluorogen-activating protein based on the GFP-like chromophores
In this paper, we present a novel genetically encoded fluorescent tag for live cell microscopy. This tag is composed of previously published fluorogen-activating protein FAST and a novel fluorogenic derivative of GFP-like chromophore with red fluorescence. The reversible binding of the novel fluorogen and FAST is accompanied by three orders of magnitude increase in red fluorescence (580-650 nm). The proposed dye instantly stains target cellular proteins fused with FAST, washes out in a minute timescale, and exhibits higher photostability of the fluorescence signal in confocal and widefield microscopy, in contrast with previously published fluorogen:FAST complexes.